Tank process for plating aluminum substrates including porous aluminum castings

摘要: An improved tank process for plating aluminum substrates which is especially advantageous porous castings and, blister-free plated produced thereby, characterized in that the piece parts are: (i) emulsion cleaned a room temperature alkaline cleaner; (ii) immersed dilute acid, inorganic, fluoride salt solution to dissolve heavy oxides and surface silicon while minimizing etching intergranular attack of substrate such, example, as cast substrate; (iii) zincate bath applying relatively thin zinc protective coating, preferably utilizing double immersion with an intermediate prolonged (1-3 min.) nitric acid soak reduce deposition rate thereby provide adhesion; (iv) non-porous strike applied directly on coating--e.g., by electroplating or electroless methods nickle-hypophosphite material maintained at approximately 190° F.; (v), metal tin bath--preferably, low pH, bath--so apply electrically conductive casting.